A cam for a press die is generally comprised of a movable cam slide having a cam surface, a cam driver for moving the cam slide by abutting against the cam surface of the cam slide, and a returning means for returning the cam slide to its original position. As the returning means, there is one in which a hole is formed in a base member of a lower die or an upper die, a guide pin of a coil spring is embedded in the cam slide, and the coil spring is inserted and fixed in the hole formed in the base in such a manner as to surround the guide pin. Additionally, there is a returning means which uses a spring unit.
According to the former returning means, to withdraw the cam slide from the cam, it is necessary to remove an end plate from the base member of the upper die or the lower die, and then to move the cam slide in such a way that the coil spring and the guide pin are located outside the hole in the base member. In a case where this movement of the cam slide cannot be effected due to an interfering object or the like, the withdrawal of the cam slide alone from the cam becomes impossible, so that, under the situation, the overall cam must be removed from the die.
On the other hand, according to the latter returning means, since this returning means is arranged such that a coil spring and the like are provided outside and below the cam slide, a large installation space is required, and it is difficult to provide a sliding guide surface below the cam slide to slidingly guide the movement of the cam slide. Since these members are provided in such a manner as to avoid the spring unit, the transverse width of the cam slide becomes large, which also requires a large installation space. Hence, this type of returning means is not very satisfactory.
The present invention has been devised in view of the above-described aspects, and it is an object of the present invention to provide a cam for a press die which makes it possible to easily withdraw the cam slide alone in the fabrication of the die, maintenance, inspection, and the like, and which makes it possible to reduce its occupying space.